JP2012166861A - Sheet storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet storage device which has improved easiness of setting sheets by causing a sheet mounting means to always stand by on a fixed position with simple constitution.SOLUTION: When a sheet cassette 10a is pulled out of the body of an image forming apparatus 100, winding pulleys 40a, 40b are rotated by the weight of a lift plate 30 in the direction in which wires 43a, 43b are drawn out. An idle gear 47 engaging with a gear part 40ab of the winding pulley 40a is also rotated. When the idle gear 47 is rotated by a predetermined amount, the engagement part 47b of the idle gear 47 is engaged with a second arm part 50c of a torsional spring 50. Since an energizing force of the torsional spring 50 is set larger than the force that rotates the idle gear 47 by the downward movement of the lift plate 30, the rotation of the idle gear 47 and the winding pulley 40a is regulated and, thus, the upper surface of the lift plate 30 is always stopped on a substantially constant position equal to or higher than the lower end part 49 of sheet supply opening parts 31a, 31b.

Description

  The present invention relates to a large-capacity paper storage apparatus that stores paper and feeds paper to an image forming apparatus such as a copying machine, a printer, or a facsimile, and more particularly to a method for improving the ability to set paper on a sheet stacking unit.

  For example, when one image forming apparatus is shared by many users, the amount of paper consumed per image forming apparatus increases. Therefore, a large capacity paper storage device has been developed in which the number of sheets that can be stored is further increased.

  Patent Document 1 discloses a large-capacity supply in which a tray on which a sheet is loaded in a tray unit is supported by an elastic support member (coil spring) so that the tray does not drop suddenly when the tray is pulled away from a drive unit. A paper device is disclosed. Further, Patent Document 2 discloses that the bottom of the paper storage unit is used without using power such as a motor by releasing the force that lifted the sheet stacking unit when the paper storage unit door was opened. A sheet feeding apparatus is disclosed in which the sheet feeding device is lowered quickly.

  Further, in Patent Document 3, by providing a brake damper having a cam and a brake plate at one end of the winding shaft of the wire, the lowering speed of the paper base is made constant regardless of the remaining amount of paper. A copier having a large capacity paper tray with reduced and increased safety is disclosed.

JP-A-5-162860 JP 2003-20129 A JP-A-5-270668

  In the large-capacity paper storage device as described above, the number of sheets to be replenished is 1,000 or more. Therefore, the user replenishes the paper into the paper storage cassette (paper storage unit) in a plurality of times when the paper is replenished. Become.

  However, in the configurations of Patent Documents 1 to 3, since the sheet stacking means such as the tray and the paper tray descends to the lowermost part or the vicinity of the lowermost part of the paper storage part, the side wall of the paper storage part becomes an obstacle when setting paper. There was a case. As a result, workability is reduced, and there is a possibility that a paper setting failure or a paper feeding failure due to this will occur.

  Although the method of Patent Document 1 can also keep the lowering position of the tray constant, when the tray is pulled away from the drive unit, the feeding of the wire and the lowering of the tray are not interlocked, so that the wire is slackened. When the slack is large, the wire may be detached from the pulley.

  In view of the above problems, an object of the present invention is to provide a sheet storage device in which sheet setting performance is improved by always waiting a sheet stacking unit at a substantially constant position with a simple configuration.

  In order to achieve the above object, the present invention provides a paper storage portion for storing paper, a replenishment opening formed in a vertical direction from the upper end of the side wall of the paper storage portion, and can be moved up and down in the paper storage portion. A lift plate, a wire that stretches the lift plate, and a take-up pulley that raises the lift plate to a predetermined position by winding a predetermined amount of the wire, and is removed from the image forming apparatus main body. In the sheet storage device in which the take-up pulley rotates in reverse due to the weight of the lift plate and the lift plate descends, an idle gear that meshes with a gear portion formed on the take-up pulley, and the idle gear And a torsion spring having a first arm portion and a second arm portion extending from the winding spring portion. The torsion spring is provided on the rotating shaft. The upper portion of the lift plate on which no sheets are loaded is replenished by fixing an engagement portion to the sheet storage portion side and providing an engagement portion for engaging the second arm portion on a side surface of the idle gear. It is characterized by being stopped at a substantially constant position above the lower end of the opening for use.

  According to the present invention, in the paper storage device configured as described above, the spring constant of the torsion spring is such that when the paper is stacked on the lift plate, the uppermost surface of the paper always has the replenishment opening regardless of the paper stacking amount. It adjusts so that it may stop at the substantially fixed position beyond the lower end part of this.

  According to the present invention, in the paper storage device configured as described above, a damper gear having a built-in torque limiter is connected to the idle gear.

  The present invention is also an image forming apparatus on which the paper storage device having the above-described configuration is mounted.

  According to the first configuration of the present invention, the rotation of the idle gear and the take-up pulley meshing with the urging force of the torsion spring is regulated so that the upper surface of the lift plate on which no paper is loaded is positioned at the lower end of the supply opening. When the paper storage device is removed from the main body of the image forming apparatus when there is no paper, the lift plate always stops at a substantially constant position above the lower end of the supply opening. Therefore, when setting a sheet by inserting a hand into the supply opening from above the paper storage unit, it is not necessary to put a hand below the lower end of the supply opening. The sheet can be set smoothly and reliably on the lift plate without being sandwiched between the sheets. Further, since the feeding of the wire from the take-up pulley and the lowering of the tray are interlocked, no loosening of the wire occurs.

  According to the second configuration of the present invention, in the paper storage device having the first configuration, when the paper is stacked on the lift plate, the top surface of the paper always has the replenishment opening regardless of the paper stacking amount. Adjust the spring constant of the torsion spring so that it stops at a substantially constant position above the lower end of the section, so that the sheet can be set in multiple times or when the sheet remains in the sheet storage section. Even when adding, it is not necessary to put a hand below the lower end of the replenishment opening, so that the hand is not sandwiched between the replenishment opening and the paper, and the paper is already on the already loaded paper. Can be set smoothly and reliably.

  According to the third configuration of the present invention, in the paper storage device having the first or second configuration, the paper storage device can form an image by connecting the idler gear and the damper gear incorporating the torque limiter. It is possible to prevent the lift plate from dropping vigorously by its own weight when it is pulled out from the apparatus main body, thereby preventing noise and improving safety.

  Further, according to the fourth configuration of the present invention, it is possible to smoothly and surely set the paper in the paper storage device by mounting the paper storage device having any one of the first to third configurations. Therefore, the image forming apparatus is excellent in operability and does not cause a paper feeding failure due to a paper setting failure.

1 is a schematic configuration diagram showing the configuration of an image forming apparatus equipped with a paper storage device of the present invention. External perspective view of the paper storage device of the present invention The side view which looked at the paper storage apparatus of this invention from the right direction of FIG. FIG. 3 is a plan view of the configuration around the take-up pulley 40a and the idle gear 47 in the paper storage device of the present invention as seen from the back side of FIG. 4 is a side view of the configuration around the take-up pulley 40a and the idle gear 47 in the paper storage device of the present invention as viewed from the right in FIG. FIG. 3 is a plan view of the configuration around the take-up pulley 40a and the idle gear 47 when the lift plate is full of paper as viewed from the back side of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus including an image reading apparatus according to an embodiment of the present invention. In FIG. 1, in an image forming apparatus 100 (here, a digital multifunction peripheral is shown as an example), when performing a copy operation, image data of a document is read and converted into an image signal by an image reading unit 6 described later. On the other hand, in the image forming unit 3 in the multifunction machine main body 2, the photosensitive drum 5 rotating in the direction A in the drawing is uniformly charged by the charging unit 4, and is based on the document image data read by the image reading unit 6. An electrostatic latent image is formed on the photosensitive drum 5 by a laser beam from an exposure unit (laser scanning unit or the like) 7, and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 8. An image is formed. The toner is supplied to the developing unit 8 from the toner container 9.

  A sheet is conveyed from the sheet feeding mechanism 10 to the image forming unit 3 via the sheet conveying path 11 and the registration roller pair 12 toward the photosensitive drum 5 on which the toner image is formed as described above. 3, the toner image on the surface of the photosensitive drum 5 is transferred onto the sheet by the transfer roller 13 (image transfer unit). The sheet onto which the toner image has been transferred is separated from the photosensitive drum 5 and conveyed to a fixing unit 14 having a fixing roller pair 14a to fix the toner image. The paper that has passed through the fixing unit 14 is sent to a paper conveyance path 15 that branches in a plurality of directions, and is fed by a path switching mechanism 21, 22 having a plurality of path switching guides provided at branch points of the paper conveyance path 15. The transport directions are sorted, and the sheets are discharged as they are (or after being sent to the sheet transport path 16 and double-sided copying) to the sheet discharge section including the first discharge tray 17a and the second discharge tray 17b.

  Although not shown, a static elimination device that removes residual charges on the surface of the photosensitive drum 5 is provided on the downstream side of the cleaning device 18. Further, the paper feed mechanism 10 is detachably attached to the multifunction machine main body 2 and includes two paper cassettes 10a and 10b for storing paper, and a stack bypass (manual feed tray) 10c provided thereabove. These are connected to the image forming unit 3 including the photosensitive drum 5 and the developing unit 8 by the paper transport path 11.

  In the paper cassettes 10a and 10b, there is provided a lift plate 30 that can reciprocate up and down, and the paper P loaded on the lift plate 30 is used as a pickup roller constituting the paper feed mechanisms 23a and 23b by the lift plate 30. The sheet is pressed and fed to the sheet conveyance path 11. The paper P in the paper cassette 10b is fed to the paper transport path 11 via the horizontal transport unit 25. The detailed configuration of the paper cassettes 10a and 10b will be described later.

  An image reading unit 6 is disposed on the upper part of the apparatus main body, and a platen (document pressing) for pressing and holding a document placed on a contact glass (not shown) of the image reading unit 6 on the upper surface of the apparatus main body. 24 is provided so as to be openable and closable, and a document conveying device 27 is provided on the platen 24. An operation panel 28 is disposed on the front surface of the image reading unit 6.

  Specifically, the sheet conveyance path 15 is first branched into left and right forks on the downstream side of the fixing roller pair 14a, and one path (the path branched in the right direction in FIG. 1) communicates with the first discharge tray 17a. It is configured as follows. The other path (the path that branches in the left direction in FIG. 1) branches into two branches via the conveying roller pair 19, and the other path (the path that branches in the left direction in FIG. 1) is the second discharge tray 17b. It is comprised so that it may communicate with. On the other hand, the other path (the path that branches downward in FIG. 1) is configured to communicate with the sheet conveyance path 16.

  2 is an external perspective view of the paper cassette 10a mounted on the image forming apparatus of FIG. 1, and FIG. 3 is a side view of the paper cassette 10a as viewed from the right in FIG. The paper cassette 10 a is a large-capacity type capable of storing 1000 sheets or more of paper, and paper is supplied from above the paper storage unit 31. A lift plate 30 that can be moved up and down is disposed in the sheet storage unit 31. The configuration of the paper cassette 10a will be described below, but the configuration of the paper cassette 10b is exactly the same.

  A pair of width restricting members 33 a and 33 b that position the paper in the width direction and a rear end restricting member 35 that aligns the rear ends of the paper are provided upright in the paper storage unit 31. By disposing the width restricting members 33a and 33b and the rear end restricting member 35 at predetermined positions, a sheet of a predetermined size can be stored at a predetermined position in the sheet storage portion 31. Further, replenishment openings 31a and 31b are formed in the wall portion on the upstream side (the back side in FIG. 2) and the downstream side (the near side in FIG. 2) of the paper storage unit 31 in the paper feeding direction. When paper is supplied from above 31, a hand is inserted into the supply openings 31 a and 31 b and the paper is stacked on the lift plate 30.

  Winding pulleys 40a and 40b are arranged below the paper cassette 10a in the paper feeding direction (left direction in FIG. 3). The take-up pulleys 40a and 40b are connected to a shaft 41 so as to be integrally rotatable, and two wires 43a and 43b are wound around the take-up pulleys 40a and 40b, respectively. The wire 43a is a fixed pulley. 45a is connected to the downstream end of the lift plate 30 in the paper feeding direction, and the wire 43b is connected to the upstream end of the lift plate 30 in the paper feeding direction via a fixed pulley 45b.

  When the paper cassette 10a is mounted in the image forming apparatus 100, a drive input coupling (not shown) on the image forming apparatus 100 main body side is connected to the take-up pulley 40a. Then, in order to smoothly and reliably feed from the paper cassette 10a, the take-up pulleys 40a and 40b are rotated in the direction to take up the wires 43a and 43b (the clockwise direction in FIG. 3) according to the decrease in the remaining amount of paper. By gradually raising the lift plate 30, the positional relationship between the uppermost part of the paper and the paper feed mechanism 23a (see FIG. 1) is kept constant.

  Further, an idle gear 47 having a diameter larger than that of the take-up pulley 40a is disposed on the side of the take-up pulley 40a. The idle gear 47 is attached to the side surface of the paper storage unit 31 by a gear attachment cover 48, and meshes with the gear part 40ab (see FIG. 5) of the take-up pulley 40a.

  4 is a plan view of the configuration around the take-up pulley 40a and the idle gear 47 as seen from the back side of FIG. 3, and FIG. 5 shows the configuration around the take-up pulley 40a and the idle gear 47 in the right direction in FIG. It is the side view seen from. 4 and 5 show a state in which no paper is placed on the lift plate 30. FIG. A winding portion 40aa for winding the wires 43a and 43b and a gear portion 40ab formed with a spur gear with which the idle gear 47 meshes are integrally formed on the winding pulley 40a.

  A torsion spring 50 is mounted on the back side of the idle gear 47. The torsion spring 50 includes a winding spring portion 50a that is extrapolated to the rotation shaft 47a of the idle gear 47, and a first arm portion 50b and a second arm portion 50c that extend in different directions from the winding spring portion 50a. The first arm portion 50 b is inserted and fixed in a fixing hole 48 a formed in the lower portion of the gear attachment cover 48. The second arm portion 50 c is engaged with an engaging portion 47 b formed on the side surface of the idle gear 47, and the vicinity of the distal end portion of the second arm portion 50 c is caused by the biasing force of the torsion spring 50 and the gear attachment cover 48. Is in pressure contact with a locking portion 48b formed at the top of the plate. The idle gear 47, the gear attachment cover 48, and the torsion spring 50 constitute a standby mechanism for causing the lift plate 30 to wait at a predetermined position.

  A damper gear 51 is connected to the upper portion of the idle gear 47. The damper gear 51 has a built-in torque limiter, which applies a load to the rotation of the idle gear 47 and keeps the lowering speed of the lift plate 30 constant. Thereby, when the paper cassette 10a is pulled out from the main body of the image forming apparatus 100, it is possible to prevent the lift plate 30 from dropping with vigor, thereby preventing noises and improving safety.

  Next, a procedure for setting paper in the paper storage unit 31 of the paper cassette 10a will be described. When all the paper in the paper storage unit 31 is fed and the paper on the lift plate 30 is exhausted, the paper cassette 10a is pulled out from the main body of the image forming apparatus 100. The drive input coupling on the image forming apparatus 100 main body side meshed with the take-up pulley 40a is released, and the take-up pulleys 40a and 40b are fed out of the wires 43a and 43b by the weight of the lift plate 30 (clockwise direction in FIG. 4). Rotate to.

  Further, due to the rotation of the take-up pulley 40a, the idle gear 47 that meshes with the gear portion 40ab of the take-up pulley 40a also rotates counterclockwise in FIG. Since the load by the damper gear 51 is applied to the idle gear 47, the rotational speeds of the idle gear 47 and the take-up pulley 40a are restricted, and the lift plate 30 is slowly lowered.

  Then, when the idle gear 47 rotates by a predetermined amount, the engagement portion 47b of the idle gear 47 is brought into the state of FIG. 4 where it engages with the second arm portion 50c of the torsion spring 50. Here, since the urging force of the torsion spring 50 is set to be larger than the force for rotating the idle gear 47 by the lowering of the lift plate 30, the rotation of the idle gear 47 and the take-up pulley 40a is restricted, and the lift plate 30 is Always stop at a substantially constant position. Specifically, the take-up pulley 40a and the idle gear 47 are arranged such that the upper surface of the lift plate 30 stops at the lower end portion 49 (see FIG. 2) of the replenishment openings 31a and 31b formed on the side wall of the paper storage unit 31. Match the phase of.

  Accordingly, when the sheet cassette 10a is pulled out from the main body of the image forming apparatus 100 when the sheet runs out, the lift plate 30 always stops so as to be substantially flush with the lower ends of the supply openings 31a and 31b. Therefore, when a paper is set by inserting a hand into the supply openings 31a and 31b from above the paper storage unit 31, it is not necessary to put a hand below the lower end portion 49 of the supply openings 31a and 31b. The paper can be set smoothly and reliably on the lift plate 30 without the hand being sandwiched between the replenishment opening and the paper.

  Further, when the paper is set on the lift plate 30, the lift plate 30 is lowered by the weight of the paper, so that the take-up pulley 40a further rotates in the clockwise direction of FIG. 4, and the idle gear 47 is further countered in FIG. Rotate clockwise. As a result, the second arm portion 50c of the torsion spring 50 is pushed by the engaging portion 47b, is separated from the locking portion 48b, and rotates in a direction approaching the first arm portion 50b (counterclockwise direction in FIG. 4). When the lift plate 30 is fully loaded with paper, the second arm portion 50c rotates approximately 90 ° from the position shown in FIG. 4 as shown in FIG.

  That is, as the amount of paper loaded on the lift plate 30 increases, the amount of rotation of the second arm portion 50c also increases, so the urging force F by the torsion spring 50 increases in proportion to the amount of paper loaded on the lift plate 30. Become. Therefore, by adjusting the spring constant of the torsion spring 50, the uppermost surface of the paper loaded on the lift plate 30 can be set to be substantially flush with the lower end portions 49 of the supply openings 31a and 31b. it can. With this configuration, even when the paper is set in a plurality of times, or when the paper is added in a state where the paper remains in the paper storage portion 31, it is below the lower end portion 49 of the supply openings 31a and 31b. Since it is not necessary to insert a hand, the hand is not sandwiched between the replenishment opening and the sheet, and the sheet can be set smoothly and reliably on the already loaded sheet.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the upper surface of the lift plate 30 when there is no paper and the uppermost surface of the paper when a predetermined amount of paper is set are substantially flush with the lower end portions 49 of the supply openings 31a and 31b. However, even if the upper surface of the lift plate 30 or the uppermost surface of the paper is positioned above the lower end portion 49 of the supply openings 31a and 31b, the hand is placed below the lower end portion 49. Since there is no need to insert it, it is possible to prevent the hand from being pinched between the supply openings 31a and 31b and the paper.

  Further, the gear diameter and gear ratio of the gear portion 40ab of the take-up pulley 40a and the idle gear 47 are also set appropriately according to the thickness and maximum take-up amount of the wires 43a and 43b used, the lifting distance of the lift plate 30, and the like. can do.

  INDUSTRIAL APPLICABILITY The present invention can be used for a large-capacity type paper storage device that lifts and lowers a lift plate with a wire. By using the present invention, a paper storage device that can maintain the upper surface of the lift plate or the uppermost surface of the paper at a position equal to or higher than the lower end of the replenishment opening portion when setting paper, and has improved paper setting properties. It can be provided simply and at low cost.

10a, 10b Paper cassette (paper storage device)
30 Lift plate 40a, 40b Winding pulley 40aa Winding part 40ab Gear part 43a, 43b Wire 47 Idle gear 47a Rotating shaft 47b Engaging part 48 Gear attachment cover 48a Fixing hole 48b Locking part 50 Torsion spring 50a Winding spring part 50b 1 arm part 50c second arm part 51 damper gear 22 inclined surface 100 image forming apparatus

Claims (4)

A paper storage section for storing paper;
A replenishment opening formed in a vertical direction from the upper end of the side wall of the paper storage unit;
A lift plate disposed so as to be movable up and down in the paper storage unit;
A wire that stretches the lift plate;
A winding pulley that raises the lift plate to a predetermined position by winding the wire by a predetermined amount;
In the paper storage device in which the take-up pulley rotates backward due to the weight of the lift plate in a state where it is removed from the image forming apparatus main body, and the lift plate is lowered.
An idle gear meshing with a gear portion formed on the take-up pulley;
A winding spring portion mounted on the rotation shaft of the idle gear, and a torsion spring having a first arm portion and a second arm portion extending from the winding spring portion;
An upper surface of the lift plate on which no sheets are stacked is provided by fixing the first arm section to the sheet storage section side and providing an engaging section for engaging the second arm section on a side surface of the idle gear. Is stopped at a substantially constant position above the lower end of the replenishment opening.   The spring constant of the torsion spring is such that when the paper is stacked on the lift plate, the uppermost surface of the paper always stops at a substantially constant position above the lower end of the replenishment opening regardless of the amount of paper loaded. The paper storage device according to claim 1, wherein the paper storage device is adjusted.   The paper storage device according to claim 1, wherein a damper gear having a built-in torque limiter is connected to the idle gear.   An image forming apparatus on which the paper storage device according to any one of claims 1 to 3 is mounted.